The Eukaryotic Mismatch Recognition Complexes Track with the Replisome during DNA Synthesis

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• DNA replication requires precise duplication of genetic material.
• Mismatch repair (MMR) proteins correct errors missed by DNA polymerase proofreading.
• The dynamic association of MMR proteins with the replication machinery is not fully understood.

Purpose of the Study:

• To investigate whether the eukaryotic mismatch recognition complex tracks with the advancing replisome during DNA replication.
• To determine the dynamics of the mismatch recognition complex (Msh2) in relation to the leading strand polymerase (Polε) during replication.
• To explore the role of PCNA in the association of the mismatch recognition complex with replicating DNA.

Main Methods:

• Utilized synchronized yeast cells.
• Employed chromatin immunoprecipitation combined with custom DNA tiling arrays (ChIP-chip).
• Analyzed the dynamics of Polε and Msh2 during the S-phase of the cell cycle.

Main Results:

• Polε was detected at active origins and replicating DNA throughout S-phase, enabling tracking of replication dynamics.
• The mismatch recognition complex (Msh2) was found to bind origins and spread with the replisome.
• In PCNA mutants, Msh2 binding dynamics were altered, indicating PCNA influences but is not solely responsible for Msh2 association.

Conclusions:

• The eukaryotic mismatch recognition complex is in proximity to the replication fork.
• This association facilitates the efficient repair of newly synthesized DNA strands.
• The findings support a model where MutS complexes are near the replisome for timely mutation repair.